1. Technical Field
The invention relates to a light source including a discharge lamp which has a pair of electrodes and a projector in which such light source is incorporated.
2. Related Art
The state of a discharge lamp which is incorporated in a discharge light-emitting type light source varies with operating time and, especially, an electrode varies its shape with time because it is consumed during lighting. The crystallization state or an impurity content of tungsten which is a component of the electrode also varies with time. A drive method of adjusting a drive waveform at the steady state by detecting the variation of states as the above by lamp voltage and the like, or a drive method of adjusting a drive waveform according to operating accumulated time by monitoring the operating accumulated time are disclosed. Examples of the related art include WO2004/066687, JP-A-2005-276623, JP-A-2004-39563, JP-A-2003-264094, JP-A-2005-310484, and JP-A-2005-209572 (Patent Document 1 to 6).
However, the above drive methods are to be performed after electric power reaches a rated value, therefore, there are some cases in which flicker occurs earlier or the life of the electrode is shorten because of insufficient control of the state of the electrode before reaching the rated value. That is, it is becoming clear that progress stages of deterioration of the electrode largely varies according to the setting of a drive waveform in initial operations until electric power reaches the rated value, accordingly, it is necessary to adjust initial operations before reaching the rated value and a steady operation after reaching the rated value in a comprehensive manner.